Physicians have an especially vast knowledge of the activity of the human brain, for they have always observed changes in psychic responses in patients with different afflictions of the brain. They have long since noticed that if certain areas of the cerebral hemispheres are injured, paralysis occurs, and when others, eyesight or hearing is a fleeted. A lesion of certain brain regions affects the speech most of all. When the temporal lobe of the left cerebral hemisphere is injured, a patient continues to hear speech, but cannot understand it. Injury to the frontal lobe of the same hemisphere mainly disturbs the articulation of sounds, while parietooccipital injuries affect the ability to count.

Some brain afflictions interfere with the ability to write or read. When sufficient observations had been accumulated, it was noticed that the lesions of the temporal lobes that made a European unable to cope with written speech had less grave consequences for a Japanese, and none for a Chinese. On the other hand, afflictions of the parietal lobe never greatly interfered with a European's faculty to write coherently, but greatly disturbed that of a Japanese, while a Chinese became absolutely incapable of writing comprehensively.

Does this mean that there are racial differences in the activity of the brain? Well, in order to answer this question, we need to discuss the organization of speech function. Just follow us in next posts.